• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1073-1080
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• 2023

The development and speed improvement of the Internet network, and the development of many platforms based on it, have brought about a rapid expansion of production and consumption of various contents. However, the existing IP-based Internet system cannot efficiently cope with such an urgent increase in data. Accordingly, an alternative called the CCN(Contents Centric Network) has emerged, enabling more efficient data transmission and reception centered on content rather than host. In this paper, we will deal with the mobility of intermediate nodes in CCN real-time streaming service, which is one of the major research fields of CCN, and minimize network overload through more efficient path switching through RSSI detection. In other words, by improving the method of selecting and switching a spare path when an intermediate node located between the requester(consumer) and the provider moves, a mechanism for managing data transmission is not interrupted and unnecessary load due to route switching does not occur in the network.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.01a
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• pp.179-185
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• 2001

Mobile agents have the unique ability to transport themselves from one system in a network to another. The ability to travel allows mobile agents to move to a system that contains services with which they want to interact and then to take advantage of being in the same host or network as the service. But most of conventional mobile agent systems require that the users or the programmer should give the mobile agent its detail behavioral script for accomplishing the given task. And during its runtime, such mobile agents just behave according to the fixed script given by its user. Therefore it is impossible that conventional mobile agents autonomously build their own plants and execute them in considering their ultimate goals and the dynamic world states. One way to overcome such limitations of conventional mobile agent systems is to develop an intelligent mobile agent system embedding a reactive planner. In this paper, we design both a model of agent mobility and a model of inter-agent communication based upon the representative reactive planning agent architecture called JAM. An then we develop an intelligent mobile agent system with reactive planning capability, IMAS, by implementing additional basic actions for agent moves and inter-agent communication within JAM according to the predefined models. Unlike conventional mobile agents. IMAS agents can be able to adapt their behaviors to the dynamic changes of their environments as well as build their own plans autonomously. Thus IMAS agents can show higher flexibility and robustness than the conventional ones.

• Journal of Korea Society of Industrial Information Systems
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• v.10 no.2
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• pp.13-20
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• 2005

An ad hoc wireless networks forms temporary network without the aid of fixed networks or centralized administration with a collection of wireless mobile hosts. In this case, it is necessary for one mobile host to enlist the aid of other hosts in forwarding a packet to its destination. This paper presents an efficient cluster-based routing protocol scheme for ad hoc networks. The cluster is used for path setup and data delivery. Our cluster-based routing algorithm is designed for the improvement of the load balance. Our simulation results show the improved performance for low mobility networks comparing with the previous works.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.9
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• pp.916-920
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• 2008

The personal workspace consists of user- specified computing environment such as user profile, applications and their configurations, and user data. Mobile computing devices (i.e., cellular phones, PDAs, laptop computers, and Ultra Mobile PC) are getting smaller and lighter to provide personal work-space ubiquitously. However, various personal work-space mobility solutions (c.f. VMWare Pocket ACE[1], Mojopac[2], u-PC[3], etc.) are appeared with the advance of virtualization technology and portable storage technology. The personal workspace can be loaded at public PC using above solutions. Especially, we proposed a framework called ubiquitous personal computing environment (u-PC) that supports mobility of personal workspace based on wireless iSCSI network storage in our previous work. However, previous u-PC could support limited applications, because it uses IRP (I/O Request Packet) forwarding technique at filter driver level on Windows operating system. In this paper, we implement OS-level virtualization technology using system call hooking on Windows operating system. It supports personal workspace mobility and covers previous u-PC limitation. Also, it overcomes personal workspace loading overhead that is limitation of other solutions (i.e., VMWare Pocket ACE, Mojopac, etc). We implement a prototype consisting of Windows XP-based host PC and Linux-based mobile device connected via WiNET protocol of UWB. We leverage several use~case models of our framework for proving its usability.

• Journal of Internet Computing and Services
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• v.10 no.4
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• pp.199-211
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• 2009

Recent advancements in wireless networks have enabled support for mobile applications to transfer data over heterogeneous wireless paths in parallel using data striping technique [2]. Traditionally, high performance data transfer requires tuning of multiple TCP sockets, at sender's end, based on bandwidth delay product (BDP). Moreover, traditional techniques like Automatic TCP Buffer Tuning (ATBT), which balance memory and fulfill network demand, is designed for wired infrastructure assuming single flow on a single socket. Hence, in this paper we propose a buffer tuning technique at senders end designed to ensure high performance data transfer by striping data at transport layer across heterogeneous wireless paths. Our mechanism has the capability to become a resource management system for transport layer connections running on multi-homed mobile host supporting features for wireless link i.e. mobility, bandwidth fluctuations, link level losses. We show that our proposed mechanism performs better than ATBT, in efficiently utilizing memory and achieving aggregate throughput.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.402-405
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• 2006

Mobile IP has been designed to have mobile host users move from place to plate without changing their IP address. Ad-hoc network is a provisional network whose mobile host users construct networks by themselves without any assistance of infra structure network, using wireless interface. In this paper we discuss the scheme with which Ad-hoc network users ran access the Internet freely, using mobile IP protocol, and Ad-hot networks are access networks in the spotlight. In this paper we propose algorithm that support enhanced mobility between two Ad-hoc networks applying mobile IP at Ad-hoc routing protocol.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.10
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• pp.1206-1216
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• 1999

이동 호스트란 시간과 공간의 제약 없이 필요한 기능을 수행하고, 또한 원하는 정보에 접근할 수 있는 휴대용 컴퓨터를 일컫는다. 이동 컴퓨팅 환경이란 이러한 이동 호스트들을 지원할 수 있도록 구성된 분산 환경이다. 따라서 이동 컴퓨팅 환경에서의 분산 알고리즘은 정적 호스트만을 고려한 기존의 분산 환경에서와는 다르게 이동 호스트의 여러 가지 특성들을 고려하여 제안되어야 한다. 즉, 이동 컴퓨팅 환경의 도래로 인하여 이동성과 휴대성, 그리고 무선 통신과 같은 특성들을 고려한 새로운 분산 상호 배제 알고리즘이 필요하다. 이제까지 이동 컴퓨팅 환경에서의 상호 배제 알고리즘은 토큰 링 구조에 기반을 두고 설계되었다. 토큰 링 구조는 이동 호스트들의 위치를 유지하기 위하여 높은 비용을 필요로 하는 단점을 가지고 있다. 본 논문에서는 균형 높이 트리(height-balanced tree)라는 새로운 모형을 제안함으로써 정적 분산 환경과 이동 분산 환경이 혼합된 환경에서 상호 배제 비용을 감소시킬 수 있는 새로운 알고리즘을 제안하며, 각 경우에 있어서의 비용을 산출하고 평가한다.Abstract The mobile host is a potable computer that carries out necessary functions and has the ability to access desirable informations without any constraints in time and space. Mobile computing environment is a distributed environment that is organized to support such mobile hosts. In that environment, distributed algorithms of which environment not only with static hosts but with mobile host's several properties should be proposed. With the emergence of mobile computing environments, a new distributed mutual exclusion method should be required to consider properties mobile computing system such as mobility, portability, and wireless communication. Until now, distributed mutual exclusion methods for mobile computing environments are designed based on a token ring structure, which have the drawbacks of requiring high costs in order to locate mobile hosts. In this paper, we propose a distributed mutual exclusion method that can reduce such costs by structuring the entire system as a height-balanced tree for static distributed networks and for networks with mobile hosts. We evaluated the operation costs in each case.

• The KIPS Transactions:PartC
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• v.12C no.4 s.100
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• pp.481-488
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• 2005

The Mobile W provides an efficient and scalable mechanism for host mobility within the Internet. However, the mobility implies higher security risks than static operations in fixed networks. In this paper, the Mobile IP has been adapted to allow AAA protocol that supports authentication, authorization, and accounting(AAA) for security and collection for accounting information of network usage by mobile nodes(MNs). For this goal, we Propose the boundary tone overlapped network structure while solidifying the security for the authentication of an MN. That is, the Proposed scheme delivers the session keys at the wired link for MN's security instead of the wireless one, so that it provides a fast and seamless handoff mechanism. According to the analysis of modeling result, the proposed mechanism compared to the existing session key reuse method is up to about $40\%$ better in terms of normalized surcharge for the handoff failure rate that considers handoff total time.

• The KIPS Transactions:PartC
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• v.11C no.5
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• pp.613-620
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• 2004

Traditionally, simulation method was used to test and evaluate the performance of communication protocol or functional elements for mobile communication service. In this Paper, PCSsim(Personal Communication System Simulator) was realized that can evaluate and review the call process of mobile communication service or to predict its performance by using the object-oriented simulation platform. PCSsim can simulate the base station and mobile host by considering the user's mobility, call generation rate and call duration time. In this paper, based on the simulation, presented the simulation results of hand-off generation ratio according to call generation, user's moving speed and call duration time both in residence area and commercial area, and it was confirmed that the hand-off rates in simulation and actual service environment have similar features. PCSsim can be used in adjusting the characteristics of base station fellowing the dynamic hand-off buffering or the characteristics of user's call in the design stage, and also can be used in building new mobile communication network by reflecting the characteristics of region where the base station is located and the mobility of the user.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.13-23
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• 2002

A mobile host is prone to failure due to lack of stable storage, low bandwidth of wireless channel, high mobility, and limited battery life on the wireless network. Many researchers have studied to overcome these problems. For high level Availability in the cellular networks, it is necessary to consider recovery from the failures of mobile support stations as well as mobile as mobile hosts. In this paper, we present modified trickle scheme for recovery from failures of Mobile Support Station based on checkpointing scheme and analyze and compare the performance. We propose and analyze the performance of two schemes : one is waiting recovery scheme for the mobile support station having the last checkpoint and the other is searching the new path to the another mobile support station having the checkpoint.